It is commonly known that chlorine is used in many parts of the world to purify water. For purposes of insuring that the water is safe for use and consumption, a small residual amount of chlorine is left in the water. It has been found that even a small amount of chlorine significantly harms or hinders the beneficial effect of the components in detergent compositions, especially the enzyme components. For example, Tivin et al, U.S. Pat. No. 3,755,085, describes such a finding in detail. Typically, the residual amount of free chlorine found in most water will attack and inactivate the enzymes contained in detergent compositions. This, obviously, eliminates or reduces the effectiveness of enzymes, thereby reducing the overall performance of typical detergent compositions.
To alleviate such problems, it has been well known to include "chlorine scavengers" or components which inactivate the free chlorine oftentimes found in washing water. Representative of the art is Pancheri et al, U.S. Pat. No. 4,810,413 and Spadini et al, U.S. Pat. No. 4,490,271, both of which are commonly assigned. Pancheri et al disclose a granular detergent composition containing a low level of ammonium salt which is protected in a particle. The particles use a polyethylene glycol carrier with a small amount of fatty acid in an irregular shaped particle having a minimum dimension of about 0.05 cm. The Spadini et al patent is directed to a detergent composition containing a surfactant, builder, and a mixture of polyethylene glycol and polyacrylate. The polyethylene glycol and polyacrylate are in a weight ratio of 1:10 to 10:1 wherein the polyethylene glycol has an average molecular weight from 1000 to 50,000 and the polyacrylate has a weight ratio from 1000 to 2000.
Both Pancheri et al and Spadini et al disclose the use of ammonium salts of polyacrylate to serve as chlorine scavengers for purposes of achieving improved cleaning performance by virtue of their inactivation of the residual chlorine present in the wash water. While such chlorine scavengers perform satisfactorily, they are not considered biodegradable to the extent desired by skilled artisans especially interested in biodegradability. The non-biodegradability characteristic of polyacrylates is especially prevalent in most detergent compositions.
There also have been a wide variety of builders used in detergent compositions for purposes of increasing the effectiveness of surfactants in detergents by softening, i.e. removing the hardness from washing solutions. For example, phosphate-based builders such as pentasodium triphosphate have been found to be effective in detergent formulations. The phosphate-based builders, however, have been held responsible for eutrophication of rivers and lakes, i.e. increasing the algae growth and oxygen consumption. Accordingly, measures have been taken to limit the content of phosphates in detergents.
Accordingly, there is a need in the art for a detergent composition which is more biodegradable as a result of incorporating more biodegradable components. Also, there is a need for such a detergent composition which exhibits improved cleaning performance.